The present invention relates to methods for providing structural reinforcement to preexisting wall structures using an adhesive material.
There are countless older buildings located in earthquake-prone regions of the world whose walls are susceptible to seismically induced damage. During an earthquake, the ground upon which the building rests moves laterally and/or vertically. These ground motions are transmitted through the building foundation to the building walls. The walls may crack as a result of the ground motions or, if the motions are sufficiently severe, the walls may fail completely and collapse. Damage caused by seismically induced forces is exacerbated in buildings with walls made from weak or brittle materials, such as clay tile, which are susceptible to failure even in the event of a relatively minor earthquake.
Accordingly, it is desirable to reinforce such building walls with bracing to resist the forces created by seismic activity. A common method for retrofitting a preexisting wall structure 6 is illustrated in FIG. 1. In this method, metal studs 12 are secured to the outside surface of each wall portion 8 of the double wall structure 6. The studs 12 extend vertically in a parallel array and are securely mounted to the outside surface of each wall portion 8 with suitable masonry ties 14, such as Helifix screws. An outer wall 16 may be mounted to the metal studs 12 to provide a conventional wall surface and hide the studs.
Although this method is adequate for its intended purpose, that is, for strengthening the wall structure to resist seismic forces, it is a costly and labor-intensive process. Moreover, stud walls added to the inside walls of a building can be intrusive and reduce usable space. In the case of a school, for example, not only would adding the stud walls reduce corridor and classroom space, it would generate the associated costs of removing or replacing items such as chalkboards, lockers, shelving, artwork and cabling.
Conventional wisdom presents obstacles for solving this problem. The cavity between the preexisting walls typically is not easily accessible and some times is enclosed even from the top. The cavity itself usually contains dust, dirt or other contaminants on the wall surfaces which are difficult to clean.
The present invention is directed toward new and nonobvious aspects of methods for retrofitting preexisting wall structures to better resist damage caused by seismic or other forces, as set forth in the claims below.